Highly efficient Tm:CaYAlO₄ laser in-band pumped by a Raman fiber laser at 1.7  μm

This paper discusses the high power, efficient operation of a Tm:CaYAlO₄ (Tm:CYA) laser in-band pumped by a Raman fiber laser at 1.7 μm. We have investigated and compared laser characteristics of 4.0 at. % and 6.0 at. % doped Tm:CYA samples with both a-cut and c-cut configurations. Up to 6.8 W of output power has been generated at 1968.3 nm using a 6.0 at. % doped and a-cut Tm:CYA crystal, corresponding to a slope efficiency with respect to incident pump power of 52.3%. Laser output from both a- and c-cut samples are nearly linearly polarized with the polarization extinction ratio (PER) reaching 24 dB for the a-cut sample.